Spiral Galaxy in Coma Berenices

Click here for higher-resolution versions:   100%, uncropped (4026x4011)  65%, uncropped (2617x2607)  40%, uncropped (1610x1604)


M100 is a magnitude 10.1 (not bright enough to see without dark skies and binoculars) spiral galaxy in Coma Berenices, 56 million light years from Earth (that's a long way--farther away than most of the galaxies I've imaged--and explains why it's apparent size is so small). It is a grand design spiral galaxy, with about 100 billion stars (perhaps one-third as many stars as our Milky Way is thought to have). It has a diameter of approximately 106,000 light years (significantly less than our Milky Way). The visible portion of M100 is about one-sixth of the angular size of a full moon.

Many galaxies have a super-massive black hole in their center; M100 is no exception.

There are many other galaxies in this image (especially in the uncropped versions linked above), most priminently NGC4312, the edge-on spiral galaxy in the upper left of the uncropped image, and the dwarf galaxies that are companions of M100 (NGC4323 and NGC4328), which appear as fuzzy blobs on the right side of M100. There are many other fuzzy blobs and/or oblong objects in the image, all galaxies.


Technical Information:

LRGB: 615:195:180:260 (That's almost 21 hours of keepers included in this image); luminance layer consists of data from 33 fifteen-minute images and 24 five-minute images; R, and G consist of fifteen-minute images; B consists of twenty-minute imagess. All images were unbinned.)

Equipment: RC Optical Systems 14.5 inch Ritchey-Chr├ętien carbon fiber truss telescope, with ion-milled optics and RCOS field flattener, at about f/9, and an SBIG STX-16803 camera with internal filter wheel (SBIG filter set), guided by an SBIG AO-X, all riding on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control: Maxim DL, controlled with ACP Expert/Scheduler, working in concert with TheSky X Professional Edition.

Processing: All images calibrated (darks, bias and sky flats), aligned, combined and cropped in Pixinsight. Color combine in Pixinsight. Some finish work (background neutralization, color calibration, deconvolution, HDR combine/HDR Mulitscale Transform of luminance data and noise reduction) done in Pixinsight; some cleanup finish work was done in Photoshop CC.

Location: Data acquired remotely with my equipment hosted by Sierra Remote Observatories, Auberry, California, USA.

Date: Images taken on many nights in May and June of 2020. Image posted June 30, 2020.

Date: Image scale of full-resolution image: 0.56 arcseconds per pixel.

Seeing: Generally excellent, with individual calibrated luminance frames varying from 1.4 to 1.9 arcsecond FWHM.

CCD Chip temperature: -25C

Copyright 2020 Mark de Regt

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